The Acute Effects of Caffeinated Black Coffee on Cognition and Mood in Healthy Young and Older Adults

Abstract

Cognitive and mood benefits of coffee are often attributed to caffeine. However, emerging evidence indicates behavioural effects of non-caffeine components within coffee, suggesting the potential for direct or synergistic effects of these compounds when consumed with caffeine in regular brewed coffee. The current randomised, placebo-controlled, double-blind, counterbalanced-crossover study compared the effects of regular coffee, decaffeinated coffee, and placebo on measures of cognition and mood. Age and sex effects were explored by comparing responses of older (61⁻80 years, N = 30) and young (20⁻34 years, N = 29) males and females. Computerised measures of episodic memory, working memory, attention, and subjective state were completed at baseline and 30 min post-drink. Regular coffee produced the expected effects of decreased reaction time and increased alertness when compared to placebo. When compared to decaffeinated coffee, increased digit vigilance accuracy and decreased tiredness and headache ratings were observed. Decaffeinated coffee also increased alertness when compared to placebo. Higher jittery ratings following regular coffee in young females and older males represented the only interaction of sex and age with treatment. These findings suggest behavioural activity of coffee beyond its caffeine content, raising issues with the use of decaffeinated coffee as a placebo and highlighting the need for further research into its psychoactive effects.

Keywords: age; caffeine; chlorogenic acids; coffee; cognition; cognitive; mood; phenolic; sex.

Figure 1

Final participant disposition. N = Number of participants; OF = Older Female; OM = Older Male; YF = Younger Female; YM = Younger Male.

Figure 2

Study visit timeline.

Figure 3

Adjusted means + standard error for salivary caffeine measured in µg/mL. Significant treatment effect **** p < 0.001.

Figure 4

Adjusted means + standard error for those cognitive measures showing significant effects of treatment. (a) Digit vigilance accuracy; (b) Digit vigilance reaction time; (c) Rapid Visual Information Processing (RVIP) reaction time. Accuracy is measured as % and reaction time in milliseconds. * p < 0.05; ** p < 0.01.

Figure 4

Adjusted means + standard error for those cognitive measures showing significant effects of treatment. (a) Digit vigilance accuracy; (b) Digit vigilance reaction time; (c) Rapid Visual Information Processing (RVIP) reaction time. Accuracy is measured as % and reaction time in milliseconds. * p < 0.05; ** p < 0.01.

Figure 5

Adjusted means + standard error for those mood measures showing significant treatment-related effects. (a) Alert; (b) Tired; (c) Headache; (d) Overall mood; (e) Mental fatigue; (f) Jittery. Ratings are measured as % along a visual analogue scale with higher values indicating greater response. YM = young male; YF = young female; OM = older male; OF = older female; * p < 0.05; *** p < 0.005; **** p < 0.001.